First Report of Pectobacterium polaris Causing Aerial Stem Rot of Potato in China

In July 2020, potato plants (cv. Xisen 6) showing characteristic symptoms of aerial stem rot were observed in a field in Fengning Manchu Autonomous County, Chengde, Hebei Province (northern China). The disease incidence in that field (5 ha in size) was more than 50%. Aerial stem rot of potato has increased in prevalence over recent years in Chengde, it can cause significant yield loss on susceptible cultivars such as Xisen 6 and Huangxin 226. Affected stem (light brown and water-soaked stem sections) pieces ca. 0.5 cm in length were surface-sterilized by dipping them in 75% ethanol for one min and then three successive rinses with sterile distilled water. Then, the tissues were soaked in 200 µl 0.9% saline for 20 min. Aliquots (20 μl) of three tenfold dilutions of the tissue specimen soaking solution were plated onto the crystal violet pectate (CVP) medium. The CVP plates were incubated at 28°C for 48 h. Colonies producing pits were restreaked and purified on Luria-Bertani (LB) agar plates. The bacterial gDNA was extracted using the EasyPure Bacteria Genomic DNA Kit (TransGen Biotech, Beijing, China). The 16S rDNA region was amplified by PCR using the universal primers 27F/1492R (Weisburg et al. 1991) and sequenced. Results of the Blastn analysis of the 16S rDNA amplicons (MZ348607, MZ348608) suggested that the isolates FN20211 and FN20222 belonged to the genus Pectobacterium. Housekeeping genes including acnA, gapA, icdA, mdh, proA and rpoS were also amplified using a set of primers (Ma et al. 2007; Waleron et al. 2008) followed by sequencing (MZ356250-MZ356261). To determine the species of the stem rot Pectobacterium isolates, multi-locus sequence analysis (MLSA) was performed with six housekeeping genes, and phylogenetic tree was reconstructed using RAxML (github.com/stamatak/standard-RAxML). No sequence variation was observed at any MLSA locus between FN20211 and FN20222. The result of phylogenetic analysis showed that the isolates clustered with P. polaris type strain NIBIO1006T, which was isolated from potato (Dees et al. 2017). And the concatenated sequence of the six loci of isolate FN20211/FN20222 is 100% identical to those of the strains PZ1 (CP046377.1) and WBC1 (GCF_011378945.1), which were isolated from potato in South Korea and from Chinese cabbage in China, respectively. Potato seedlings (cv. Xisen 6 and Favorita) were inoculated with the isolates FN20211 and FN20222 by injecting 100 µl of bacterial suspensions (108 CFU·mL-1) into the upper parts of the stems of potato plants, or injected with 100 µl of 0.9% saline as control. The seedlings were grown at 25°C and 50% relative humidity. Three days after inoculation, only the bacteria-inoculated seedlings showed disease symptoms resembling to those observed in the field. Bacterial colonies were obtained from the infected stems and were identified using the same PCR primers as described above. Therefore, P. polaris isolates FN20211 and FN20222 fulfill Koch’s postulates for aerial stem rot of potato. P. polaris causing blackleg and soft rot on potato plants has been reported in European countries including Netherlands, Norway (Dees et al. 2017) and Poland (Waleron et al. 2019), and also in Pakistan (Sarfraz et al. 2019) and Russia (Voronina et al. 2021). To our knowledge, this is the first report of P. polaris causing aerial stem rot of potato in China. The stem rot poses a significant threat to the local potato industry, and further research on epidemiology and disease management options is needed.

First Report of Pectobacterium versatile Causing Aerial Stem Rot of Potato in China

Pectobacterium species cause blackleg, soft rot and stem rot in potato and many other vegetable crops (Charkowski 2015). In July 2020, potato plants showing characteristic symptoms of aerial stem rot were observed in a field (cv. Xisen 6) in Fengning Manchu Autonomous County, Chengde, Hebei Province (North China). The disease incidence in that field (5 ha in size) was more than 50%. Putative pectolytic bacteria were obtained from symptomatic stem tissues (light brown and water-soaked stem sections) by culturing on the crystal violet pectate (CVP) medium. Bacterial colonies producing pits, were restreaked and purified on Luria-Bertani (LB) agar. The isolates causing stem rot were gram negative and rod shaped, negative for oxidase, urease, indole production, gelatin liquefaction and acid production from maltose and D-sorbitol. All isolates were catalase positive, produced acid from lactose, rhamnose, saccharose, raffinose and D-arabinose, and were tolerant to 5% NaCl, and able to utilize citrate. The bacterial gDNA was extracted using the EasyPure Bacteria Genomic DNA Kit (TransGen Biotech). The 16S rDNA region was amplified by PCR using the universal primer pair 27F/1492R and sequenced. Result of the Blastn analysis of the 16S rDNA amplicons (MZ379788, MZ379789) suggested that the isolates FN20111 and FN20121 belonged to the genus Pectobacterium. To determine the species of the stem rot Pectobacterium isolates, multi-locus sequence analysis (MLSA) was performed with six housekeeping genes acnA, gapA, icdA, mdh, proA and rpoS (MZ403781-MZ403792), and phylogenetic tree was reconstructed using RAxML v8.2.12 (https://github.com/stamatak/standard-RAxML). The result of phylogenetic analysis showed that the stem rot Pectobacterium isolates FN20111 and FN20121 clustered with P. versatile (syn. ‘Candidatus Pectobacterium maceratum’) strains CFBP6051T (Portier et al. 2019), SCC1 (Niemi et al. 2017) and F131 (Shirshikov et al. 2018). And the isolates FN20111 and FN20121 were more closely related to the type strain CFBP6051T than to strains SCC1 and F131. Potato seedlings (cv. Xisen 6 and Favorita) were inoculated with the isolates FN20111 and FN20121 by injecting 100 µl of bacterial suspensions (108 CFU·mL-1) into the upper parts of the stems of potato plants, or injected with 100 µl of 0.9% saline solution as control. The seedlings were grown at 28°C and 50% relative humidity. Three days post-inoculation, only the bacteria-inoculated seedlings showed diseased symptoms resembling to those observed in the field. Bacterial colonies were obtained from the infected stems and were identified using the same PCR primers of housekeeping genes as described above, fulfill Koch’s postulates. P. versatile causing soft rot and blackleg on potato plants has been reported in Finland (Niemi et al. 2017), Russia (Shirshikov et al. 2018), Netherlands (Portier et al. 2019), Poland (Waleron et al. 2019) and in New York State (Ma et al. 2021). To our knowledge, this is the first report of P. versatile causing aerial stem rot of potato in China.

Removal of perchlorate by a lab-scale constructed wetland using achira (Canna indica L.)

Achira (Canna indica L.) has not yet been tested for its potential in removing perchlorate (ClO4−) from wastewater. In this study, constructed wetlands with and without achira were used to investigate the removal efficiency and removal mechanism of perchlorate. The results showed that more ClO4− was removed by the wetlands with achira relative to those without. Perchlorate removal in the wetlands without achira decreased with time, whereas perchlorate in the wetlands with achira was stably removed. In terms of ClO4− content, the achira tissues were in the descending order of: leaf > aerial stem > flower or rhizome > root. Perchlorate was concentrated in leaves (more than 55.8%) rather than in root (less than 0.67%). Mass balance calculation showed that plant uptake accounted for 5.81–7.34% of initial ClO4− input, while microbial degradation accounted for 29.39–62.48%. The wetlands with achira were favorable for soil microorganism growth and proliferation and in turn ClO4− biodegradation. Furthermore, the effluent pH increased in achira wetland columns and in turn promoting ClO4− removal. The results indicating that the wetlands with achira promote ClO4− removal by improving the rhizosphere environment.

A new species of Viola (Violaceae) from Guangdong Province, China

Viola huizhouensis (Violaceae), a new species from Xiangtoushan National Nature Reserve of Guangdong Province in China, is described and illustrated. The new species is most similar to V. guangzhouensis, but it can be easily distinguished by its much stouter rhizome, lack of aerial stem, dense pubescence of the basal pedicel and the whole plant. Our phylogenetic analysis, based on ITS sequences, confirms that the new species belongs to V. sect. Diffusae.

Miticidal Evaluation of Different Non-Volatile Bioactive Compounds Extracted from Ferula Oopoda Against Apple Mites

The research was administered in order to spot the miticidal effect of wild grown plant namely Ferula oopoda against the mites that destroy the leaf tissue and also the colour of the fruit in trees. The theme was to get the herb’s (1) aerial, stem and root part about 1 kg and was soaked for about 7 days and then extract the oil by the help of vaccum rotary evaporator, the extracted oil is then allowed to stay for a day in HCl (0.2M), then the solution is filtered and then some charcoal is added to the filtrate and now, it is put on the Bunsen burner for a while, now the HCl extract is again filtered and basified by the addition of Sodium hydroxide (5M), the yellow colour is the indication of basification and now the ppts are collected that are formed over the filter paper, the ppts are dried and later on sprayed on the apple mites and their mortality rates are noted at exposure time of 6, 12, 24, 36 and 48h. It may be a new revolutionary technique that can be economical as well as environment friendly as the oil is only lethal for the target apple mites and doesn’t not harm human health.

Rohdea dangii (Asparagaceae), a new species from northwestern Vietnam

Rohdea dangii, a new species from limestone areas of Son La and Dien Bien Provinces in northwestern Vietnam, is described and illustrated. It is apparently most closely related to R. tonkinensis described from northern Vietnam, for these two species share an elongate aerial stem with no cataphylls (except for those at the base of the peduncle), narrowly elliptic leaf blades and filaments conspicuously incrassate in the lower decurrent portions. It is, however, readily distinguishable mainly by the longer, thicker rhizome, non-sheathing amplexicaule leaf blades, half-terete peduncle, much shorter bracts mostly not exceeding the flowers, and crateriform perigone tube. The taxonomic relationships of the new species to R. wattii and two other species with an aerial stem were also briefly discussed.

Effect of Explants and Low Cost Medium on Morphogenic Response of Aerial Stem and Rhizome Bud Explants of Turmeric (Curcuma longa L.) for Plant Regeneration

This study was done to select suitable explants and low cost medium for plant regeneration of turmeric. Therefore, the different explants were excised from the aerial stems and rhizome buds and surface sterilized. The sterilized explants were cultured on MS medium fortified with 2.0 mg/l BAP. From the survived aerial stem explants, 0.5 cm long vertical half of the aerial stem explants exhibited somatic embryogenic response (69.7%). The highest morphogenic response (74%) of shoot bud initiation was observed from the top slice of the surviving rhizome bud explants. Further, Yara Mila complex fertilizer, which is an ideal granular fertilizer mixture, was used as an alternative to MS medium. Three different concentrations of Yara Mila complex fertilizer (1.0, 3.0, and 5.0 g/l ) supplemented with 2.0 mg/l BAP each were tested with the MS medium fortified with 2.0 mg/l BAP (control treatment) for in vitro establishment from aerial stem explants and top slice of the rhizome bud explants. Both explants were surface sterilized and cultured on MS medium and different concentrations of Yara Mila complex fertilizer fortified with 2.0 mg/l BAP. From the survived explants, aerial stem explants exhibited somatic embryogenic response (69.7%) and shoot bud initiation (74%) on normal MS media. The higher performances were observed in 1.0 g/l concentration of complex fertilizer incorporated medium with 51% embryogenic response from the aerial stem explants and 52.3% shoot bud formation response from the top slice of the rhizome bud. The cost of 1 kg complex fertilizer was Rs. 182. It could be concluded that complex fertilizer is a cost effective alternative medium for MS medium for in vitro propagation reducing the cost of the substituted ingredients by 99.87% in the tissue culture of turmeric.

STUDY ON THE RESPONSE OF THE SAFARI POTATO VARIETY TO SPRAYING WITH THE NUTRIENT SOLUTION HORTIPHYTE AND THE SEAWEED EXTRACT STYMULANT FORTE

An experiment was carried out in vegetable fields, Department of Horticulture and Gardening, College of Agriculture and Forestry, Mosul University for the spring season 2018. To find out the effect of foliar feeding of a seaweed extract (Stymulant forte) in concentrations of (0, 3 and 6) g. L-1 and Hortiphyte nutrient solution in concentrations (0, 2 and 4) ml. L-1 on the potato crop class A (Safari). The experiment was carried out with 9 factor treatments according to the Randomized complete block design (RCBD), with three replications. The results of the studied treatments were tested according to the polynomial Duncan test at a probability level of 0.05. The results showed the superiority of the treatment of spraying seaweed extract at concentration 6 g. L-1 was significant, given the highest significant values for average stem length and number of aerial stem. plant-1 , and the percentage of dry matter for the plant%, while spray treatment was superior to 3 g. L-1 was significant in the leaf area index, treatment of spraying feeding solution in two or four ml concentrations. L-1 was significant at average stem length (cm) and number of aerial stem. plant-1 , with an increase of (5.10 and 15.35%), respectively; compared to the comparison treatment. The two characteristics of chlorophyll and the percentage of dry matter per plant were not different from the comparison treatment. As for the results of the total yield, it was given the treatment of spraying the seaweed extract at a concentration of 6 g. L -1 is the most significant value for the number of tubers. Plant-1 , average weight of tuber (kg), yield of one plant (kg), percentage of dry matter for tubers%, and production rate per area (tons. ha-1) compared to the rest of the treatments, and reached (13.111 tuber. Plant-1 , 0.126 kg, 1.63 kg, 16.127%, 87.390 ton. ha-1 ), respectively. The treatment of spraying the nutrient solution affected the 2 or 4 mL concentrations. 1 liter-1 morally by giving the highest significant values for the average weight of the tuber, the yield of one plant and the percentage of dry matter for tubers and total production per area compared to the no-spray treatment, and with an increase of 11.11 kg, 11.68 kg, 7.43%, 11.54 tons. ha-1 ), respectively. It did not differ from the comparison treatment in terms of the number of tubers. plant

External mechanical cues reveal core molecular pathway behind tissue bending in plants

SummaryTissue folding is a central building block of plant and animal morphogenesis. In dicotyledonous plants, hypocotyl folds to form hook after seedling germination that protects their aerial stem cell niche during emergence from soil. Auxin response factors and auxin transport are classically thought to play a key role in this process. Here we show that the microtubule-severing enzyme katanin contributes to hook formation. However, by exposing hypocotyls to external mechanical cues mimicking the natural soil environment, we reveal that auxin response factors ARF7/ARF19, auxin influx carriers, and katanin are dispensable for apical hook formation, indicating that these factors primarily play the role of catalyzers of tissue bending in the absence of external mechanical cues. Instead, our results reveal the key roles of the non-canonical TMK-mediated auxin pathway, PIN efflux carriers and cellulose microfibrils as components of the core pathway behind hook formation in presence or absence of external mechanical cues.